The present invention generally relates to molded plastic containers of the type commonly used for a variety of purposes including storage of both food items and non-food items, such containers preferably being adapted to receive an appropriate seal or lid. More specifically, the invention is concerned with containers of this type which, rather than being of a rigid construction as with a conventional bowl, are collapsible or foldable to a compact position when empty to facilitate convenient storage.
Such containers, in the form of cups, bowls, and the like, are generally known in the art and take many forms. These include collapsible cups or glasses wherein the glass is formed of telescopically stacked annular wall elements which slide relative to each other between a fully extended position and a collapsed position. As the wall elements are not integrally formed and slide freely relative to each other, there is a substantial possibility of leakage, and use other than as a temporary drinking vessel is not practical.
Another form of collapsible container more pertinent to the present invention is illustrated in U.S. Pat. No. 5,439,128, issued to Fishman on Aug. 8, 1995. In the Fishman container, the wall elements are integrally molded and consist of a series of vertical and angled elements alternately stacked to define the container wall. The elements, at the angular joint therebetween, are integrally joined by thin film hinges about which the wall elements fold. The actual downward folding and collapsing of the Fishman elements requires that the elements flex in order to accommodate the folding motion. This necessity for an actual flexing of the elements themselves, in addition to the folding at the film hinges, appears to be so significant as to, at least in some instances as illustrated in FIG. 3 of Fishman, require significant central relief grooves in each of the inclined wall elements which would appear to cause an inherent weakening of these wall elements.